This specification relates to information retrieval.
The Internet provides an opportunity for users to share images and for content providers to disseminate information by way of images. Identification of images that are relevant to a particular query can be based, for example, on textual information associated with the image and visual characteristics of the image. For example, a search system can identify images that are associated with textual information that is related to the query and an image relevance model that has been trained for a particular query can provide a measure of visual relevance of an image to the particular query based on visual characteristics of the image.